Disposable inhaler with pull-off seal

ABSTRACT

The invention relates to a disposable breath-actuated inhaler comprising a housing forming an air flow path open at both ends, wherein one end forms an air inlet and one end forms an air outlet. The housing includes a compartment for storing a pharmaceutical powder to be inhaled which is located close to the air inlet and covered by a thin foil which seals the compartment in an airtight way. The foil can be removed from the compartment from outside the housing. Additionally, the housing has a constriction adjacent the powder compartment such that a turbulent air stream will be obtained at the constriction upon inhalation which will lift the powder out from the compartment and mix the powder into the air stream.

This application is a continuation of application Ser. No. 07/984,424,filed as PCT/SE91/00601 Sep. 10, 1991, now abandoned.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a breath-actuated disposable inhaler ofthe kind having a generally tubular shape having two ends, one endforming an air inlet and one end forming an air outlet, the inhalercontaining a pharmaceutical powder comprising particles of a respirablesize which is to be inhaled.

BACKGROUND OF THE INVENTION

Disposable, breath-actuated inhalers of the kind described above are forinstance disclosed in WO 89/01348, U.S. Pat. No. 4,265,236 andEP-A-0404454.

EP-A-0404454 discloses a disposable, breath-actuated inhaler comprisinga chamber for a pharmaceutical powder, said chamber being provided withan air inlet and with an air outlet. The air inlet and outlet arecovered by a common cover. The powder is disposed loosely in saidcomparatively large chamber which means that the powder not necessarilywill be located at that location at which the air flow is mostefficient.

U.S. Pat. No. 4,265,236 discloses a tubular disposable, breath-actuatedinhaler comprising a flexible tube, the ends of which normally beingsealingly inserted into each other. This kind of seal will notnecessarily be moisture-proof. There furthermore is a risk that someamount of the powder may fall out of the inhaler when the ends of thetube are pulled apart.

WO 89/01348, in the embodiment most of interest here, discloses atubular, disposable inhaler which is sealed in both ends by means oftwist-off caps. The pharmaceutical powder is loosely disposed in theinhaler and, as in the other inhalers described above, there is a riskthat some powder is lost when the inhaler is opened.

The objects of the invention are to provide a disposable inhaler of thekind described above in which the dose of pharmaceutical powder can bedetermined accurately and in which the pharmaceutical powder can bestored hermetically sealed and moisture-proof. The dose delivered bydifferent specimens of the same inhaler should generally be constant.The inhaler finally should be easy to prepare for use and easy to use aswell as being easy and cheap to manufacture.

BRIEF DESCRIPTION OF THE INVENTIVE CONCEPT

The above objects are achieved in that the disposable inhaler isprovided with the features set forth in the appended main claim.Advantageous embodiments are set forth in the dependent claims.

BRIEF DESCRIPTION OF THE APPENDED DRAWINGS

FIG. 1 shows a perspective view of an inhaler according to theinvention,

FIG. 2 shows a perspective view of an inhaler according to FIG. 1 butshowing the two main parts of the inhaler in an unassembled state,

FIGS. 3A-3C show different stages in the opening of the powdercompartment of the inhaler of FIG. 1,

FIG. 4 shows an end view of the air inlet of the inhaler in FIG. 1,

FIGS. 5-7 show different possible embodiments of the constrictionadjacent the powder compartment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION.

A preferred embodiment of the invention is disclosed in FIGS. 1-4. InFIG. 1 the inhaler can be seen in a fully assembled condition and readyfor use. As can be seen, the inhaler essentially comprises two elongatemain parts, an upper part 1 which is made of a moulded sheet of plasticmaterial and a lower part 2 preferably made of aluminium foil laminatedwith plastic. The upper part 1 is U-shaped with a substantiallyrectangular shape. The width of the upper part is several times theheight. The lower part is generally flat and the two parts thus form atubular housing defining an air conduit or air flow path with an airinlet 4 and an air outlet 5. A part-spherical depression or recess 3indicated with a dashed line is located close to the air inlet 4. Therecess 3 forms a powder compartment and is covered by a tape 6 whichpreferably is made of aluminium foil, also laminated with plastic.

As indicated, the end of the part of the tape 6 covering the recess 3 islocated between the recess 3 and the air inlet 4. The tape is attachedto the lower part 2 around the powder compartment by means of arelatively weak weld 22 which can be seen in FIG. 2. The end of the tapeis attached by a comparatively large and thus stronger weld in front ofthe compartment, as seen in the intended direction of the air flow. Thefree part of the tape 6 is bent backwards over the recess 3 and extendsout through the air inlet 4. The free part of the tape is guided andheld by two conical projections 7,8 extending downwards from the upperpart 1.

A constriction in the flow path in the form of a ridge 9 orientedperpendicularly relative to the direction of the flow path is locatedabove the powder compartment. The ridge is formed as a depression 9 inthe upper part 1. The ridge is delimited at each end by an abutment 10.

The inhaler is further provided with deaggregation means after thepowder compartment, as seen in the direction of the intended air flowthrough the inhaler. These deaggregation means comprise a number ofoblique planar surfaces which are oriented at an angle of about 30°relative to the longitudinal direction of the inhaler, it surprisinglyhaving been found that the most efficient angle of a planar surfacerelative to the air flow direction for disintegrating powderagglomerations is about 30°. Since the air flow will be deflected tosome extent by the planar surface, the flow direction will not coincidefully with the longitudinal direction, but the above angle has beenchosen as being the best compromise. The planar surfaces are orientedgenerally perpendicularly relative to the lower part 2, or at least asperpendicularly as the method of manufacturing the inhaler allows. Theplanar surfaces are located in such a way that their projections onto across-sectional plane substantially cover the entire cross-section ofthe inhaler. The projections preferably should overlap to some extent inorder to ensure that any larger particles or agglomerations entrained inthe air flow will impact on at least one such surface. In the preferredembodiment the planar surfaces 11, 12, 13, 14, 15, 16 are located on theupstream ends of two pairs of indentions 17, 18; 19, 20, formed into thesides of the upper part 1 and on the upstream end of a centraldepression 21 located between said indentations forming an island in theflow path. The downstream ends of said indentations and said depressiontaper in the direction of the air flow and have a smooth, rounded shapein order to obtain good aerodynamic conditions without any areas wherethe powder entrained in the air flow could settle.

The two main parts of the inhaler are shown separated in FIG. 2. Apartfrom the details shown in FIG. 1, the powder compartment 3 is shownopened, the tape 6 having been pulled outwardly through the air inlet.The shape of the (broken) weld 22 can be seen on the tape 6 and aroundthe powder compartment 3. As can be seen, the shape of the weld has beenchosen to be the perimeter of a square oriented with one diagonalparallel with the longitudinal extent of the inhaler. This means thatthe disengagement of the tape from the lower part 2 will be facilitatedsince the tearing action will both start and end at a corner. Since theweld holding the inner end of the tape is broad and strong, the userwill feel when the compartment has been uncovered by means of theincreased resistance.

FIGS. 3A-3C show different stages in the opening of the powdercompartment 3 by pulling the tape 6, thus exposing the powder 23.

The end view in shown in FIG. 4 more clearly illustrates theinter-relationship between the upper part 1, the lower part 2, thepowder compartment 3, the tape 6, the conical projections 7, 8, theridge 9 and the abutments 10.

When the inhaler is to be used, the inhaler is held more or lesshorizontal with the flat half 2 facing downwards. The free end of thetape 6 is pulled outwardly and the powder in the powder compartment 3 isexposed. The two conical projections 7, 8 will hold the tape 6 flatagainst the lower part 2 and thus prevent the tape from occluding theconstriction in front of the powder compartment. The user then insertsthe air outlet into the mouth and inhales through the inhaler. Theresultant air flow through the inhaler will become very turbulent in theregion of the constriction and the pharmaceutical powder will be liftedout of the powder compartment and mixed with the air flow. Any particlesadhering to the tape may also be entrained with the air flow since thepart of the tape originally covering the powder compartment also willlie directly in the flow path.

Tests have shown that the dose leaving a typical powder compartment(about 0.5 mg) located at a constriction having an area of about 10-12mm² will remain essentially constant at air flow rates varying from 30l/min to 60 l/min.

The powder-laden air will then flow from the constriction to thedeaggregation means. The angle of attack of the oblique surfaces willentail that the lighter particles, i.e. the particles within therespirable range, <6 μm, will be deflected from the surface withoutsticking thereto and thus mainly will follow the air flow, whereas theheaver particles and agglomerates will impact on and rebound from theplanar surfaces and in this way be broken up into smaller particles. Asmentioned above, an angle of about 30° may be optimal.

In this case tests again have shown that the percentage of particleswithin the respirable range in the dose to be inhaled will remainsubstantially constant at air flow rates ranging from 30 l/min to 60l/min.

That the dose of respirable particles remains substantially constantover a wide range of air flows is important in order to minimize thedifference between patients with different inhalation capacities.

It should be noted that the tubular shape of the inhaler makes itpossible to mount a rubber ball or similar over the air inlet. By themeans thereof the powder could be ejected from the inhaler into thethroat of the patient in synchronization with the breathing of thepatient by a helper if the patient should be incapable to use theinhaler by himself.

As mentioned above, the lower part 2 of the inhaler as well as the tape6 preferably are made of aluminium foil laminated or coated with asuitable plastic. The aluminium will ensure the desired protectionagainst moisture whereas the plastic will ensure that the tape can bewelded to the lower part and that the lower part can be welded to theupper part. The lower part may for instance consist of a aluminium foilhaving a thickness of 45μ which on one side is covered with a layer oforiented polyamide which is 25μ thick and on the other side is coveredby a layer of polypropene which is 60μ thick. The upper part ispreferably made of polypropene being 300 or 400μ thick. The upper partcan be transparent so that the user can see if the dose has been ejectedfrom the powder compartment.

The tape may be made of a laminate having a "peel"-effect comprisingpolyester, aluminium and a layer comprising a polymer mixture ofpolybuten and polypropene.

The choice of material in the inhaler should be adapted to the drug tobe used. The above materials have been chosen with a specific drug(budesonide) in mind, these materials releasing a dose of this drug moreeasily.

The composition of the pharmaceutical powder of course is quite optionaland the powder may for instance comprise a pure active substance, amixture of different active substances or a mixture of activesubstance(s) with adjuvant(s). It should be pointed out that the scopeof choice of drugs is widened considerably due to the moisture-proofcontainment of the drug in the powder compartment.

The inhaler may be manufactured in the following way. A series ofhalf-spherical indentations are formed in a strip of laminated aluminiumfoil in order to shape powder compartments. The indentations are filledwith drugs and are topped off by means of scrapers, which will ensure asubstantially uniform size of the different doses. An aluminium tapelaminated with plastic is then welded over each indentation.

The lower parts are then welded to upper parts and the strip is cut toform individual inhalers which are ready for packaging and use. Theupper parts are moulded from sheets of plastic. In the mouldingprocedure care should be taken to ensure that the side walls of theupper part are as perpendicular as possible relative to the upper sidein order to ensure an air flow which is as uniform as possiblethroughout the entire cross-section of the inhaler. The function of theabutments 10 primarily are to prevent that the ridge forming theconstriction is distorted during the welding process.

POSSIBLE MODIFICATIONS OF THE INVENTION

The invention of course can be modified in many ways within the scope ofthe appended claims.

Thus the ridge 9 forming the constriction can be designed in differentways in order to enhance the lifting action of the air flow on thepowder. Some examples thereof can be found in FIGS. 5-7.

FIG. 5 illustrates how the ridge 9 can be provided with a small hole 24centrally above the powder compartment 3. When the patient inhalesthrough the inhaler, additional air will be directed more or lessperpendicularly down into the powder compartment, thus enhancing theturbulent action in the vicinity of the powder compartment;

FIGS. 6 and. 7 illustrate two alternative embodiments wherein the ridgehas been provided with an edge 25 resp 26 oriented along thelongitudinal extent of the ridge and which also will direct some airflow more directly into the powder compartment.

These embodiments will however require a higher degree of precision inthe manufacturing in order to obtain the desired effect than theembodiment described above and will therefore be more difficult tomanufacture.

The ridge 9 forming the constriction has been illustrated as beinggenerally trapezoid in cross-section and as being generally rectilinearin longitudinal section. It should however be pointed out that theconstriction may be shaped in many different ways within the scope ofthe appended claims.

The powder compartment can of course have another shape than ahalf-spherical shape and may for instance be elliptical, the minor axisthereof being parallel with the direction of the air flow, or may beotherwise trough-shaped. It is of course also possible to have severalindentations, for instance if it is desired to increase the dose in anexactly defined way.

The projections 7,8 can be shaped otherwise than conically and may forinstance be shaped such that they direct a greater part of the air flowmore directly past the powder compartment. They also could be integratedwith the abutments 10.

The deaggregation means can be designed in other ways than in the formof planar surfaces oriented at an angle of about 30° relative to thedirection of the air flow. This angle can be varied and the surfaceitself does not necessarily have to be planar.

The material in the lower part and the tape does not necessarily have tocomprise aluminium and may be any plastic material having the necessaryimpermeability and stiffness or having been treated to have theseproperties.

It is also conceivable to make the inhaler from a single sheet which isrolled or folded after having been moulded in an appropriate way.

We claim:
 1. A disposable breath-actuated inhaler comprising: a housingforming an air flow path being open at both ends, one end forming an airinlet and one end forming an air outlet, said housing further comprisinga compartment for storing a pharmaceutical powder to be inhaled, whereinthe compartment is located close to the air inlet and communicates withthe air flow path through a compartment outlet, wherein the compartmentis sealed from the air flow path by a tape covering the compartmentoutlet, wherein the inner end of the tape is attached to a lower part ofsaid housing between the air inlet and the compartment, the tapeextending past and being attached to the edges of the compartment outletby means of a relatively weak weld, the tape then being bent backwardaway from the air outlet so as to extend through the air inlet, saidhousing being shaped with a constriction of the air flow path at thecompartment outlet such that a turbulent air stream will be obtained atthe constriction upon inhalation which will lift the pharmaceuticalpowder out from the compartment, through the compartment outlet and mixthe pharmaceutical powder into the turbulent air stream which exits theair outlet.
 2. The inhaler according to claim 1, wherein said housing isformed of two main parts comprising: a molded upper part and a generallyflat lower part having a recess extending below the lower part to formthe compartment, said upper and lower parts being joined together alongtheir longitudinal sides.
 3. The inhaler according to claim 2, whereinthe molded upper part is molded from a thin sheet of plastic.
 4. Theinhaler according to claim 3, wherein the constriction is formed as adepression in the upper side of the molded upper part, the constrictionis oriented transversely relative to the longitudinal axis of saidhousing and the constriction is located above the compartment formed inthe generally flat lower part of said housing.
 5. The inhaler accordingto claims 2, 3 or 4, wherein the lower part is made of aluminum foillaminated with plastic.
 6. The inhaler according to claim 1, wherein thethin foil is in the shape of a tape having one free end extending outthrough the air inlet, said tape being attached around the edges of thecompartment by means of at least one relatively weak weld.
 7. Theinhaler according to claim 1, wherein the relatively weak weld forms apoint facing downstream in order to facilitate an initiation of atearing action along the relatively weak weld when the tape is to bepulled out through the air inlet in order to expose the powder.
 8. Theinhaler according to claim 1 or 7, further comprising at least oneprojection extending downward from the upper part of said housingpositioned between the compartment and the air inlet for holding thetape against the lower part of said housing in order to prevent the tapefrom obstructing the air flow path.
 9. The inhaler according to claim 1,2, 3 or 4 further comprising a means for deaggregation located in theair flow path between the compartment and the air outlet.
 10. Theinhaler according to claim 9, wherein said means for deaggregationcomprises a plurality of planar surfaces oriented obliquely relative tothe longitudinal axis of said housing, said plurality of planar surfacesbeing disposed generally perpendicularly to the plane of the lower partof said housing, a projection of said plurality of planar surfaces ontoa cross-section of the housing substantially covering saidcross-section.
 11. The inhaler according to claim 1, wherein the airinlet and the air outlet are positioned at opposite ends of thelongitudinal axis of said housing.